Light source device and optical engine

ABSTRACT

A light source device includes a plurality of laser modules and a beam combiner. Each laser module includes a first laser diode configured to emit a first laser beam and a second laser diode configured to emit a second laser beam. The beam combiner has a first dichroic mirror region and a second dichroic mirror region. The first dichroic mirror region is configured to transmit the first laser beam going out from the first laser module, and to reflect the second laser beam going out from the second laser module. The second dichroic mirror region configured to transmit the second laser beam going out from the first laser module, and to reflect the first laser beam going out from the second laser module.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/821,309 filed Mar. 17, 2020 which claims priority to Japanese PatentApplication No. 2019-054511 filed on Mar. 22, 2019, the entire contentsof which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to a light source device and an opticalengine that includes such a light source device.

Conventional projectors have employed discharge lamps, e.g., ultra-highpressure mercury lamps and xenon lamps, as light sources. In recentyears, projectors utilizing light-emitting diodes (LEDs) as the lightsources, which excel in terms of power consumption and environmentalload as compared to discharge lamps, have been put to practical use.

Semiconductor laser devices (hereinafter referred to as “laser diodes”or simply “LDs”) have higher radiance than do LEDs, and are beingapplied to various fields. Projectors having a hybrid-type light sourcein which a phosphor is excited by laser beams emitted from LDs, suchthat light of a necessary wavelength region is obtained, have been putto practical use.

High-radiance light sources which are capable of combining laser beamsthat are emitted from red, green, and blue LDs, without using anyphosphor, are under development. Japanese Laid-Open Patent PublicationNo. 2012-88451 discloses a light source device which merges laser beamsthat are emitted from a red laser, a green laser, and a blue laser byusing dichroic prisms. Japanese Laid-Open Patent Publication No.2008-3125 discloses a light source device which merges laser beams ofdifferent polarization directions by using a polarization beam combiner.

SUMMARY

A light source device which emits light with an increased radiance andwhich is suitable for downsizing, and an optical engine that generatesillumination light with high in-plane uniformity, are being desired.

Embodiments of the present disclosure provide a light source device witha novel structure which can combine a plurality of laser beams ofdifferent wavelength bands for an enhanced radiance, and an opticalengine that includes such a light source device.

In one embodiment, a light source device according to the presentdisclosure includes: a plurality of laser modules including a firstlaser module and a second laser module, each laser module including atleast one first laser diode configured to emit a first laser beam and atleast one second laser diode configured to emit a second laser beam; anda beam combiner. The second laser beam has a wavelength which is longerthan a wavelength of the first laser beam. The beam combiner includes: afirst dichroic mirror region configured to transmit the first laser beamgoing out from the first laser module, and to reflect the second laserbeam going out from the second laser module; and a second dichroicmirror region configured to transmit the second laser beam going outfrom the first laser module, and to reflect the first laser beam goingout from the second laser module. The first laser module is disposed ata position for obliquely irradiating a rear side of the beam combinerwith the first laser beam and the second laser beam going out from thefirst laser module. The second laser module is disposed at a positionfor obliquely irradiating a front side of the beam combiner with thefirst laser beam and the second laser beam going out from the secondlaser module.

In one embodiment, another light source device according to the presentdisclosure includes: a first laser module, a second laser module, and athird laser module, each including at least one first laser diodeconfigured to emit a first laser beam having a wavelength λ₁ and beinglinearly-polarized along a first direction, and at least one secondlaser diode configured to emit a second laser beam having a wavelengthλ₂ which is longer than the wavelength λ₁ and being linearly-polarizedalong the first direction or along a second direction which isorthogonal to the first direction. The light source device furtherincludes a beam combiner disposed between the third laser module and thesecond laser module and configured to combine the first laser beam andthe second laser beam emitted from each of the first laser module, thesecond laser module, and the third laser module. The beam combinerincludes: a first optical film including a first dichroic filmconfigured to transmit light of the wavelength λ₁ and to reflect lightof the wavelength λ₂; a second optical film including a λ/2 phase platefor the wavelength λ₂ configured to rotate a polarization direction oflight of the wavelength λ₂ by 90 degrees, and a second dichroic filmconfigured to transmit light of the wavelength λ₂, transmit light of thewavelength λ₁ being polarized along the first direction, and to reflectlight of the wavelength λ₁ being polarized along the second direction,the second optical film and the first optical film being provided sideby side along a first plane; a third optical film including a thirddichroic film configured to transmit light of the wavelength λ₂ and toreflect light of the wavelength λ₁; and a fourth optical film includinga λ/2 phase plate for the wavelength λ₁ configured to rotate apolarization direction of light of the wavelength λ₁ by 90 degrees, anda fourth dichroic film configured to transmit light of the wavelengthλ₁, transmit light of the wavelength λ₂ not passing through the λ/2phase plate for the wavelength λ₂, and to reflect light of thewavelength λ₂ having passed through the λ/2 phase plate for thewavelength λ₂, the fourth optical film and the third optical film beingprovided side by side along a second plane. The first plane and thesecond plane intersects at a line of intersection between the firstoptical film and the second optical film and between the third opticalfilm and the fourth optical film. The first laser module is disposed ata position for obliquely irradiating rear sides of the first opticalfilm, the second optical film, the third optical film, and the fourthoptical film with the first laser beam and the second laser beam goingout from the first laser module. The second laser module is disposed ata position for obliquely irradiating front sides of the second opticalfilm and the first optical film with the first laser beam and the secondlaser beam going out from the second laser module. The third lasermodule is disposed at a position for obliquely irradiating front sidesof the third optical film and the fourth optical film with the firstlaser beam and the second laser beam going out from the third lasermodule.

In one embodiment, an optical engine according to the present disclosureincludes: at least one light source device as any of the above; opticswhich a laser beam emitted from the at least one light source device isincident to; a spatial light modulator to be irradiated with the laserbeam having passed through the optics; and projection optics to projectthe laser beam having been modulated by the spatial light modulator.

According to various embodiments of the present disclosure, a lightsource device which can combine a plurality of laser beams of differentwavelength bands for an enhanced radiance, and an optical engine thatincludes such a light source device, are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing an exemplaryarrangement of a light source device according to a first embodiment ofthe present disclosure.

FIG. 2A is a schematic plan view of a first laser module according tothe first embodiment.

FIG. 2B is a cross-sectional view of the first laser module in FIG. 2Aas taken along line IIB-IIB.

FIG. 3A is a plan view of a beam combiner according to the firstembodiment.

FIG. 3B is a cross-sectional view of the beam combiner in FIG. 3A astaken along line IIIB-IIIB.

FIG. 4A is a cross-sectional view schematically showing anotherexemplary arrangement for the beam combiner.

FIG. 4B is a cross-sectional view schematically showing still anotherexemplary arrangement for the beam combiner.

FIG. 5 is a cross-sectional view schematically showing another exemplaryarrangement for the light source device according to the firstembodiment.

FIG. 6 is a plan view showing an exemplary arrangement for a lasermodule according to the first embodiment.

FIG. 7 is a plan view showing another exemplary arrangement for a lasermodule according to the first embodiment.

FIG. 8 is a plan view showing still another exemplary arrangement for alaser module according to the first embodiment.

FIG. 9 is a plan view showing another exemplary arrangement for the beamcombiner according to the first embodiment.

FIG. 10A is a diagram showing an exemplary wiring arrangement in a lasermodule according to the first embodiment.

FIG. 10B is a diagram showing another exemplary wiring arrangement in alaser module according to the first embodiment.

FIG. 11A is a diagram showing a light source device according to avariant of the first embodiment.

FIG. 11B is a diagram showing a light source device according to anothervariant of the first embodiment.

FIG. 12 is a cross-sectional view showing another exemplary arrangementfor the light source device according to the first embodiment.

FIG. 13 is a cross-sectional view showing an exemplary arrangement of alight source device according to a second embodiment of the presentdisclosure.

FIG. 14A is a cross-sectional view showing an exemplary arrangement of abeam combiner in FIG. 13.

FIG. 14B is a schematic exploded diagram showing the beam combiner ofthe exemplary arrangement in FIG. 14A.

FIG. 15 is a diagram showing the functionality of a beam combineraccording to the second embodiment.

FIG. 16 is a perspective view showing another exemplary arrangement forthe beam combiner according to the second embodiment.

FIG. 17A is a diagram showing the operation of the light source deviceaccording to the second embodiment.

FIG. 17B is another diagram showing the operation of the light sourcedevice according to the second embodiment.

FIG. 17C is a diagram showing the operation of a light source deviceaccording to a variant of the second embodiment.

FIG. 18 is a cross-sectional view showing an exemplary arrangement of anoptical engine according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, with reference to the attached drawings, embodiments of thepresent disclosure will be described in detail. The followingembodiments are generic or specific examples. Various implementationsthat are described in the present specification can be combined with oneanother, whenever such combination makes sense.

Embodiment 1

FIG. 1 is a cross-sectional view schematically showing an exemplaryarrangement of a light source device 1000 according to a firstembodiment of the present disclosure. In the attached drawings includingFIG. 1, the X axis, the Y axis, and the Z axis which are orthogonal toone another are schematically shown for reference. In FIG. 1, the X axisis perpendicular to the plane of the figure, and is oriented in thedepth direction. The orientation of the light source device 1000 duringuse may be arbitrary, without being limited to the illustratedorientation of the light source device 1000.

The light source device 1000 according to the present embodimentincludes a plurality of laser modules 100 and a beam combiner 200. Laserbeams which are emitted from the plurality of laser modules 100 aremerged or combined by the beam combiner 200. The beam combiner 200functions as a multiplexer. Although an actual laser beam would have athickness (i.e., a beam diameter) along a direction which isperpendicular to its propagation direction, for simplicity, the attacheddrawings only illustrate its center axis as a straight line, whileignoring the beam diameter of the laser beam. Since the combined laserbeam is to go out in a positive direction along the Y axis, the positiveside along the Y axis will be referred to as the “front side”, whereasthe negative side along the Y axis will be referred to as the “rearside”.

In the illustrated example, the plurality of laser modules 100 include afirst laser module 100 ₁ and a second laser module 100 ₂ which aredisposed orthogonal to each other. Each of the first laser module 100 ₁and the second laser module 100 ₂ includes first laser diodes 10, secondlaser diodes 12, and third laser diodes 14. Hereinafter, a laser diodewill simply be referred to as an “LD”.

Each first LD 10 emits a first laser beam of a wavelength λ₁, whereaseach second LD 12 emits a second laser beam of a wavelength λ₂. Thewavelength λ₁ is shorter than the wavelength λ₂. Each third LD 14 emitsa third laser beam of a wavelength λ₃, such that the wavelength λ₃ isbetween the wavelength λ₁ and the wavelength λ₂. As used herein, the“wavelength of a laser beam” is synonymous with the lasing wavelength ofthe LD, i.e., peak wavelength. Generally speaking, even LDs which areproduced under the same conditions and possess the same structure maydiffer in lasing wavelength from one another, and any given LD may evenfluctuate depending on the operating environment. The values of λ₁, λ₂and λ₃ pertain to wavelength bands of different colors, such that eachof them may have some spectral width or variation within the respectivecolor wavelength band. The term “wavelength of a laser beam” will beexplained later in more detail.

Next, with reference to FIG. 2A and FIG. 2B, an exemplary arrangement ofthe first laser module 100 ₁ will be described. The second laser module100 ₂ is similar in structure, shape, and size to the first laser module100 ₁, but differs therefrom with respect to its orientation. Therefore,description concerning the arrangement of the second laser module 100 ₂will not be redundantly repeated here. FIG. 2A is a schematic plan viewof the first laser module 100 ₁, and FIG. 2B is a cross-sectional viewof the first laser module 100 ₁ in FIG. 2A as taken along line IIB-IIB.

In the example of FIG. 2A, a total of eight LDs 10, 12 and 14 aredisposed in rows and columns (an array of 2 rows by 4 columns) on aprincipal face of a base (or support) 100C for constructing a package.Specifically, in each row extending along a direction (row direction)which is parallel to the Z axis direction, one third LD 14, one first LD10, and two second LDs 12 are arranged in this order. In a first columnextending along a direction parallel to the X axis direction, two thirdLDs 14 are arranged in one row along the X axis direction. In a secondcolumn, two first LDs 10 are arranged in one row, along the X axisdirection. In each of third and fourth columns, two second LDs 12 arearranged in one row along the X axis direction. In the presentembodiment, the number of second LDs 12 mounted on one laser module 100₁ is twice the number of first LDs 10 or twice the number of third LDs14. The reason for this will be described later.

FIG. 2A shows a border line C1 which divides the eight LDs 10, 12 and 14into two groups of LDs. In FIG. 2A, on the right side of the border lineC1, the LDs 12 which lase at a wavelength that is longer than areference wavelength Λ are mounted; on the left side of the border lineC1, the LDs 10 and 14 which lase at a wavelength that is shorter thanthe reference wavelength Λ are mounted. The technological significancebehind such an arrangement, where the two-dimensional array of LDs 10,12 and 14 is divided into two different regions in accordance with theirrelatively higher or lower lasing wavelengths with respect to thereference wavelength Λ, will be described later.

Generally speaking, an LD may be classified as an ultraviolet LD, a blueLD, a green LD, a red LD, or an infrared LD, for example, depending onits lasing wavelength band. When the light source device 1000 is to beused as a light source of visible light, the LDs 10, 12 and 14 are to beselected from among those LDs which emit visible light. In the presentembodiment, the first LDs 10 are blue LDs, the second LDs 12 are redLDs, and the third LDs 14 are green LDs. The lasing wavelength of eachblue LD is from 430 nm to 480 nm, e.g. from 450 nm to 470 nm. The lasingwavelength of each green LD is from 500 nm to 540 nm, e.g. from 520 nmto 540 nm. The lasing wavelength of each red LD is from 620 nm to 660nm, e.g. from 630 nm to 650 nm. Therefore, the aforementioned referencewavelength Λ may be selected within a range from 540 nm to 620 nm, whichis between an upper limit value for the lasing wavelength of a green LDand a lower limit value for the lasing wavelength of a red LD, forexample.

The blue LDs and the green LDs may mainly be composed of nitridesemiconductor materials. Examples of nitride semiconductor materialsinclude GaN, InGaN, and AlGaN, for example. Each red LD may mainly bemade of a gallium arsenide-based semiconductor material, for example. IfLDs whose lasing wavelength is shorter than the near-infrared region areadopted and their optical output power is increased, dust or the like inthe ambient may adhere to an end face (emitter) during operation owingto the optical trapping or optical dust collection effect, thus possiblylowering the optical output power. The substance that adheres to the LDsmay not necessarily be dust, but may also be some deposit that isgenerated as volatilized organic matter chemically reacts the laserbeam. Deteriorations associated with adhering matter will be moreoutstanding as the wavelength of the laser beam becomes shorter and theoptical output power higher. In order to avoid this problem, each of theplurality of laser modules 100 may desirably be a hermetic packagehousing the LDs 10, 12 and 14.

In the present embodiment, as shown in FIG. 2B, a laser beam which isemitted from the end face (emitter) of each LD 10, 12 or 14 along the Zaxis direction is reflected by a corresponding mirror 15, so as tochange its orientation to the Y axis direction. Each laser beam istransmitted through a light-transmitting member 16 and a collimatinglens 18 that are attached to the base 100C, so as to propagate along theY axis direction. The collimating lens 18 reduces the divergence angleof the diverging laser beam that is emitted from the respective LD 10,12 or 14, thus collimating it. The orientations of the LDs 10, 12 and 14are not limited to this example. In FIG. 2B, if the end face of each LD10, 12 or 14 were oriented in the Y axis direction, for example, a laserbeam emitted from each LD 10, 12 or 14 would be incident on thecollimating lens 18 without even being reflected by a mirror; in thiscase, the mirrors can be omitted. Each LD 10, 12 or 14 may be mounted ona metal mount (not shown) that has a high thermal conductivity.

The first laser module 100 ₁ and the second laser module 100 ₂ arechosen from among a plurality of laser modules 100 having the samearrangement, for example, and are disposed orthogonally as shown inFIG. 1. Each laser module 100 that is included in the light sourcedevice 1000 according to the present embodiment includes a plurality ofLDs 10, 12 and 14 that emit laser beams of three primary color of red,green, and blue. Since the laser beams which are obtained from theplurality of laser modules 100 are combined (multiplexed) by the beamcombiner 200, radiance can be increased approximately twofold.

In the present embodiment, the red LDs have a smaller luminous flux thanthose of the blue LDs and the green LDs, and therefore the number ofsecond LDs 12 that are mounted on each laser module 100 is twice thenumber of first LDs 10 or twice the number of third LDs 14. This allowswhite light to be reproduced, by subjecting the LDs of the respectivecolors to time division driving. Without being limited thereto, thenumber of LDs for each color can be adjusted so that necessary lightwill be obtained.

Without being limited to the above example, the numbers of first LDs 10,second LDs 12, and third LDs 14 may each be one, or two or any numberthat is three or greater. In one example, the first laser module 100 ₁may be similar in structure, shape, and size to the second laser module100 ₂, but embodiments of the present disclosure are not necessarilylimited to this example.

The characteristics of the red LDs may be more susceptible totemperature-dependent fluctuations than are the characteristics of theblue LDs and the green LDs. Moreover, the blue LDs have a greaterefficiency of power conversion than that of the green LDs, and thereforethe blue LDs generate smaller amounts of heat than do the green LDs.Therefore, the green LDs may desirably be remoted from the red LDs. Inthe present embodiment, columns of blue LDs (first LDs 10) are disposedbetween the columns of red LDs (second LDs 12) and the columns of greenLDs (third LDs 14). This allows the emission characteristics of the redLDs (second LDs 12) to be stabilized.

In an embodiment of the present disclosure, the lasing wavelength of thefirst LDs 10 which are mounted on one laser module 100 does not need tobe exactly equal to the lasing wavelength of the first LDs 10 which aremounted on the other laser module 100. The same is also true of thesecond LDs 12. For example, when the first LDs 10 are blue LDs, thelasing wavelength of the first LDs 10 which are mounted on each lasermodule 100 may be within a range from 430 to 480 nm. Therefore, in thepresent disclosure, that “the wavelength of a first laser beam isshorter than the wavelength of a second laser beam” means that thelasing wavelengths of the first LDs that are mounted on each lasermodule are within a first wavelength region (e.g. a blue wavelengthregion), and that the lasing wavelengths of the second LDs that aremounted on each laser module are within a second wavelength region (e.g.a red wavelength region) that is located on the longer wavelength sideof the first wavelength region. Similarly, given that a plurality offirst LDs 10 are mounted on a single laser module 100, their lasingwavelengths do not need to be exactly equal. The same is also true ofthe second LDs 12 and the third LDs 14.

In an optical engine for displaying full-color images, for a broadercolor gamut, it is desirable for the respective colored light of red(R), green (G), or blue (B) needed for displaying to be monochromaticlight of a narrow spectral width that is specific to that color.Therefore, in the case where a light source device according to thepresent disclosure is applied to such an optical engine, it ispreferable for the peak wavelength of a laser beam that is emitted fromeach LD to be contained within a narrow wavelength range (e.g. a rangespanning 12 nm) for the respective color. For example, in the pluralityof first LDs 10 being a plurality of blue LDs, the wavelength λ₁, i.e.,the peak wavelength of the first laser beam that is emitted from eachfirst LD 10, may desirably be contained in the range from 459 to 471 nm,for example. In the case of adopting blue LDs which were fabricated sothat the design value of their central wavelength would be 465 nm,within the same light source device 1000, the peak wavelengths of thefirst laser beams that are emitted from the respective first LDs 10 mayexhibit different values in a range from 459 to 471 nm, for example. Itis considered that this much wavelength variation is not likely to causeimage quality deteriorations. Similar degrees of wavelength variationcan be tolerated also for the green LDs and red LDs.

Hereinafter, for simplicity, a laser beam which is emitted from a blueLD may be referred to as a B beam, a laser beam emitted from a green LDas a G beam, and a laser beam emitted from a red LD as an R beam. InFIG. 1, the signs “R”, “G”, and “B” represent an R beam, a G beam, and aB beam, respectively.

Next, with reference to FIG. 3A and FIG. 3B, an exemplary arrangement ofthe beam combiner 200 will be described. FIG. 3A is a plan view of thebeam combiner 200, and FIG. 3B is a cross-sectional view of the beamcombiner 200 in FIG. 3A as taken along line IIIB-IIIB.

In the illustrated example, the beam combiner 200 has a first dichroicmirror region 21 and a second dichroic mirror region 22. The firstdichroic mirror region 21 is a region which transmits a first laser beamof the wavelength λ₁ and a third laser beam of the wavelength λ₃, butwhich reflects a second laser beam of the wavelength λ₂. On the otherhand, the second dichroic mirror region 22 is a region which reflects afirst laser beam of the wavelength λ₁ and a third laser beam of thewavelength λ₃, but which transmits a second laser beam of the wavelengthλ₂. The regions 21 and 22 exhibiting such wavelength selectivity may be,as shown in FIG. 3B, realized by multilayer dielectric films 21L and 22Lof different wavelength selectivities being provided at the front side200F of the beam combiner 200, on a transparent substrate 20 thereof.Examples of dielectrics to compose the multilayer dielectric films 21Land 22L include SiO₂, ZrO₂, TiO₂, Al₂O₃, Ta₂O₅, Nb₂O₅, SiN, AlN, SiON,AlON, and so on. The wavelength selectivity may be adjusted by therefractive index and layer thickness of the dielectric. Anantireflection coating may desirably be formed on the rear side 200B ofthe beam combiner 200.

The transparent substrate 20 may be made of a monocrystal, polycrystal,or glass material. A region in which a multilayer dielectric film 21Lthat selectively transmits light of the wavelength λ₁ or λ₃ andselectively reflects light of the wavelength λ₂ can be utilized as thefirst dichroic mirror region 21. A region in which a multilayerdielectric film 22L that selectively reflects light of the wavelength λ₁or λ₃ and selectively transmits light of the wavelength λ₂ can beutilized as the second dichroic mirror region 22. The multilayerdielectric film 21L and the multilayer dielectric film 22L can be formedby depositing the respective dielectric films on the transparentsubstrate 20 by sputtering or the like, and patterning them bylithography or the like, for example.

The beam combiner 200 may be produced by various methods, and may havevarious arrangements. For example, as shown in FIG. 4A, a component part26A functioning as the first dichroic mirror region 21 and a componentpart 26B functioning as the second dichroic mirror region 22 may becoupled together. Alternatively, as shown in FIG. 4B, the arrangementmay include a transparent substrate 20 having a portion functioning asthe first dichroic mirror region 21 and a component part 28 being fixedon the transparent substrate 20 and functioning as the second dichroicmirror region 22.

FIG. 1 is referred to again. In the example of FIG. 1, the first lasermodule 100 ₁ is disposed at a position for obliquely irradiating therear side 200B of the beam combiner 200 with a laser beam. On the otherhand, the second laser module 100 ₂ is disposed at a position forobliquely irradiating the front side 200F of the beam combiner 200 witha laser beam.

More specifically, a B beam (wavelength λ₁) and a G beam (wavelength λ₃)going out from the first laser module 100 ₁ are incident on the rearside 200B of the first dichroic mirror region 21 of the beam combiner200, and transmitted through the first dichroic mirror region 21. On theother hand, a B beam (wavelength λ₁) and a G beam (wavelength λ₃) goingout from the second laser module 100 ₂ are incident on the front side200F of the second dichroic mirror region 22 of the beam combiner 200,and reflected by the second dichroic mirror region 22.

An R beam (wavelength λ₂) going out from the first laser module 100 ₁ isincident on the rear side 200B of the second dichroic mirror region 22of the beam combiner 200, and transmitted through the second dichroicmirror region 22. On the other hand, an R beam going out from the secondlaser module 100 ₂ is incident on the front side 200F of the firstdichroic mirror region 21 of the beam combiner 200, and reflected by thefirst dichroic mirror region 21.

FIG. 1 illustrates each laser beam that is transmitted through the beamcombiner 200 and each laser beam that is reflected by the beam combiner200 as if located on different optical axes. However, as shown in FIG.5, each transmitted laser beam and each reflected laser beam may belocated on the same axis.

In an embodiment of the present disclosure, as has been described withreference to FIG. 2A, LDs which lase at a wavelength that is shorterthan the reference wavelength Λ and LDs which lase at a wavelength thatis longer than the reference wavelength Λ are allocated in regions aspartitioned by the border line C1. FIG. 6 is a plan view schematicallyshowing a relationship between: two regions partitioned by the borderline C1; and colors (RGB) associated with the lasing wavelengths of theLDs to be disposed in the respective regions. Although the aboveembodiment illustrates that the green LDs (G) and the blue LDs (B) arearranged on one side of the border line C1, embodiments of the presentdisclosure are not limited to this example. For example, as shown inFIG. 7, the red LDs (R) may be disposed on the right side of the borderline C1, while only the blue LDs (B) may be disposed on the left side.In this case, the first laser module 100 ₁ alone will not constitute alight source device that is complete with the three colors of RGB, butthe second laser module 100 ₂ may include green LDs (G) on the left sideof the border line C1, for example, thereby realizing the three colorsof RGB. Applications of the light source device 1000 are not limited tolight sources of display devices. The light source device 1000 may alsobe used as a light source for anything other than display devices; andthe light source device 1000 may be used as a non-white light source.Although the example of FIG. 6 illustrates that the green LDs (G) andthe blue LDs (B) are disposed on the same side, the green LDs (G) may bemoved over to the right side of the border line C1, so as to be disposedon the same side as the red LDs (R). In that case, the reflection andtransmission characteristics exhibited by the dichroic mirror regions 21and 22 need to drastically change between the wavelength λ₁ and thewavelength λ₃. Regarding the three colors of RGB, the interval betweenthe wavelength λ₁ and the wavelength λ₂ is generally wider than theinterval between the wavelength λ₁ and the wavelength λ₃, which factmakes it easy to adopt the example shown in FIG. 6.

FIG. 8 is a plan view showing a variant of the first laser module 100 ₁.In this example, the LDs on the first laser module 100 ₁ are allocatedinto four regions as partitioned by a border line C1 and a border lineC3 that is orthogonal to the border line C1. When the first laser module100 ₁ and the second laser module 100 ₂ have the arrangement shown inFIG. 8, the beam combiner 200 may have a structure shown in FIG. 9, forexample. In the beam combiner 200 of FIG. 9, first dichroic mirrorregions 21 and second dichroic mirror regions 22 are diagonally disposedin four regions as partitioned by a border line C2 and a border line C4that is orthogonal to the border line C2.

Thus, plenty of freedom is provided for the positioning of LDs on thefirst laser module 100 ₁ and the second laser module 100 ₂. Howeverstill, in order to allow the first LDs 10, the second LDs 12, and thethird LDs 14 to each independently emit light of a different color, forexample, there are some preferable positioning layouts. Hereinafter,this aspect will be described.

FIG. 10A is a diagram showing an example wiring interconnection on thefirst laser module 100 ₁ shown in FIG. 2A. In the example of FIG. 10A,the first laser module 100 ₁ includes: LDs 10, 12 and 14 which areprovided on a principal face of the base 100C; a plurality of wires 100Lelectrically connecting LDs associated with the same color; and aplurality of lead terminals 100T for electrically connecting the wires100L to external driving circuits (not shown). Two first LDs 10 providedside by side along the X axis direction are connected in series, via awire 100L, between a lead terminal 100T denoted as “B+” and a leadterminal 100T denoted as “B−”. Similarly, two third LDs 14 provided sideby side along the X axis direction are connected in series, via a wire100L, between a lead terminal 100T denoted as “G+” and a lead terminal100T denoted as “G−”. As for the second LDs 12, in each column extendingalong the X axis direction, two second LDs 12 are connected in series,via a wire 100L, between a lead terminal 100T denoted as “R+” and a leadterminal 100T denoted as “R−”. A p-side electrode and an n-sideelectrode of each LD 10, 12 or 14 are electrically connected to nearbywires 100L.

Thus, since a plurality of LDs associated with the same color aremounted side by side in a distinct column for each color, an efficientelectrical connection can be realized with a small number of leadterminals 100T. LDs associated with different colors have differentelectrical resistances, which makes it desirable that their drivingcircuits be also different. By connecting the first LDs 10, the secondLDs 12, and the third LDs 14 to respectively different lead terminals,the first LDs 10, the second LDs 12, and the third LDs 14 can beindependently driven. This also permits time division-based lightemission of each of the colors of RGB respectively.

FIG. 10B is a plan view showing an exemplary arrangement in which threeLDs are provided side by side in each column. Even when the number ofLDs is thus increased, there is no need to increase the number of leadterminals 100T. The number of LDs in each column may differ from columnto column. The types and numbers of respective LDs are to be determinedin accordance with their optical output powers, so that uniform whitelight will be obtained after merging.

Without being limited to direct connection via the wires 100L, the LDsadjoining along the column direction may also be electrically connectedby a conductor layer, or by way of a conductor layer or the like. Thepositions and shapes of the lead terminals 100T, and the pattern of thewires 100L may be arbitrary, without being limited to the illustratedexample.

FIG. 11A is a diagram showing a light source device 1100 according to avariant of the present embodiment. The light source device 1100 includesa plurality of light source units 1000A and 1000B each having a similararrangement to the light source device 1000 in FIG. 1. Laser beams whichare emitted from the light source units 1000A and 1000B are propagatedin substantially the same direction by optics including a lens 400. Inthe example of FIG. 11A, the light source unit 1000A on the left sideand the light source unit 1000B on the right side are in amirror-symmetric relative positioning; however, embodiments of thepresent disclosure are not limited to this example. FIG. 11B is adiagram showing a light source device 1200 according to another variant.Instead of the light source unit 1000B in FIG. 11A, the light sourcedevice 1200 includes a light source unit 1000C. With respect to thelight source unit 1000A on the left side, the light source unit 1000C isof such a relationship that the orientation of the second laser module100 ₂ is turned upside down, and that the beam combiner 200 is rotatedclockwise by 90 degrees around an axis which is parallel to the X axis.

Thus, with the construction shown in FIG. 11A or FIG. 11B, laser beamswhich are emitted from the four laser modules 100 are combined. Thenumber of light source units to be included in each light source device1100, 1200 is not limited to two. The construction shown in FIG. 11A orFIG. 11B may alternatively be arranged along a direction (the X axisdirection) which is perpendicular to the plane of the figure.

Note that, as has been described earlier, it is not necessary for onelaser module 100 to include all of the first LDs 10, the second LDs 12,and the third LDs 14. For example, in a light source device 1300 shownin FIG. 12, the first laser module 100 ₁ and the second laser module 100₂ respectively include: at least one first LD 10 which emits a firstlaser beam(s) of the wavelength λ₁ (B beam); and at least one second LD12 which emits a second laser beam(s) of the wavelength λ₂ (R beam). Thefirst dichroic mirror region transmits a first laser beam (B beam) whichis emitted from the first laser module 100 ₁, and reflects a secondlaser beam (R beam) which is emitted from the second laser module 100 ₂.The second dichroic mirror region 22 transmits a second laser beam (Rbeam) which is emitted from the first laser module 100 ₁ and reflects afirst laser beam (B beam) which is emitted from the second laser module100 ₂.

By itself, the light source device 1300 shown in FIG. 12 does not outputthree colors of RGB. Therefore, in the case where the light sourcedevice 1300 is used as a light source for a display device such as alaser projector, laser light of the missing color (e.g. green) may beprovided by another light source. For example, in the light sourcedevice 1100 of FIG. 11A, the light source units 1000A and 1000B may havethe structure of the light source device 1300 shown in FIG. 12. In thatcase, for example, the light source unit 1000A may emit an R beam and aB beam, while the light source unit 1000B may emit an R beam and a Gbeam.

Embodiment 2

Next, with reference to FIGS. 13 through 17C, a light source deviceaccording to a second embodiment of the present disclosure will bedescribed.

First, with reference to FIG. 13, an exemplary overall construction of alight source device 1400 according to the present embodiment will bedescribed. The light source device 1400 includes a first laser module100 ₁, a second laser module 100 ₂, and a third laser module 100 ₃ whichare oriented in directions each differing by 90 degrees. In the presentembodiment, the laser modules 100 ₁, 100 ₂ and 100 ₃ all have the samearrangement, and therefore may be collectively referred to as the “lasermodules 100”. In the present embodiment, too, the positive directionalong the Y axis is referred to as “the front side”, whereas thenegative direction along the Y axis is referred to as “the rear side”.

Each of the plurality of laser modules 100 includes at least one firstLD 10 which emits a first laser beam(s) (wavelength λ₁) and at least onesecond LD 12 which emits a second laser beam(s) (wavelength λ₂), suchthat the relationship λ₁<λ₂ is satisfied. λ₁ is contained in e.g. theblue wavelength region (430 to 480 nm), whereas λ₂ is contained in e.g.the red wavelength region (620 to 660 nm). Hereinafter, the first laserbeam (wavelength λ₁) will be referred to a B beam, and the second laserbeam (wavelength λ₂) as an R beam. Each laser module 100 may beidentical in arrangement to the laser module 100 shown in FIG. 1.Herein, for simplicity, the description will not detail at least onethird LD to emit a third laser beam (wavelength λ₃); the third laserbeam (wavelength λ₃) is to be treated similarly to the first laser beam(wavelength λ₁).

The light source device 1400 includes a beam combiner 300 which combinesa plurality of laser beams emitted from the laser modules 100.Hereinafter, with reference to FIG. 14A and FIG. 14B, the beam combiner300 according to the present embodiment will be described in detail.FIG. 14A is a cross-sectional view showing an exemplary arrangement ofthe beam combiner 300, and FIG. 14B is a schematic exploded diagramthereof.

The beam combiner 300 according to the present embodiment is produced bycombining four triangular prisms 31, 32, 33 and 34 which are transparentwith respect to visible light. Hereinafter, a “triangular prism” willsimply be referred to as a “prism”. The prisms 31 to 34 each have theshape of a geometrical triangular prism extending along the X axisdirection, and may be made of a monocrystal, polycrystal, or glassmaterial. In the illustrated example, a cross section of eachgeometrical triangular prism taken parallel to the YZ plane is anisosceles triangle having a vertex angle of 90 degrees. The first prism31 and the second prism 32 adjoin each other via an imaginary firstplane J. Similarly, the third prism 33 and the fourth prism 34 adjoineach other via the first plane J. Moreover, the first prism 31 and thefourth prism 34 adjoin each other via an imaginary second plane K,whereas the second prism 32 and the third prism 33 adjoin each other viathe second plane K. As shown in FIG. 14B, the first plane J and thesecond plane K intersect each other at a line of intersection Oextending along the X axis direction.

The beam combiner 300 as such includes: a first optical film 41 and asecond optical film 42 provided side by side along the first plane Jwith the line of intersection O interposed therebetween; and a thirdoptical film 43 and a fourth optical film 44 provided side by side alongthe second plane K with the line of intersection O interposedtherebetween. As will be described later, the optical films to 44 havewavelength selectivity and/or polarization selectivity, and exhibitdifferent optical characteristics (reflectance and transmittance)depending on the wavelength and polarization of incident light.Moreover, the second optical film 42 and the fourth optical film 44include half-wave plates (λ/2 phase plates) for light of respectivelydifferent wavelengths.

FIG. 14B schematically shows a state before the prisms 31, 32, 33 and 34are combined into one beam combiner 300. The first prism 31 includes afirst slope 31 a and a second slope 31 b, whereas the second prism 32includes a first slope 32 a and a second slope 32 b. The third prism 33includes a first slope 33 a and a second slope 33 b, whereas the fourthprism 34 includes a first slope 34 a and a second slope 34 b.

In the example shown in FIG. 14B, the first optical film 41 is providedon the first slope 31 a of the first prism 31, whereas the secondoptical film 42 is provided on the second slope 34 b of the fourth prism34. The third optical film 43 is provided on the second slope 31 b ofthe first prism 31, whereas the fourth optical film 44 is provided onthe first slope 32 a of the second prism 32. Such positioning is only anexample. For instance, the first optical film 41 may be provided on thesecond slope 32 b of the second prism 32, and the second optical film 42may be provided on the first slope 33 a of the third prism 33.

FIG. 13 is referred to again.

The first laser module 100 ₁ is disposed at a position for obliquelyirradiating the rear side of the first and fourth optical films 41 and44 with a B beam (wavelength λ₁), and obliquely irradiating the rearside of the second and third optical films 42 and 43 with an R beam(wavelength λ₂).

The second laser module 100 ₂ is disposed at a position for obliquelyirradiating the front side of the second optical film 42 with a B beam(wavelength λ₁), and obliquely irradiating the front side of the firstoptical film 41 with an R beam (wavelength λ₂).

The third laser module 100 ₃ is opposed to the second laser module 100 ₂with the beam combiner 300 interposed therebetween, and is disposed at aposition for obliquely irradiating the front side of the third opticalfilm 43 with a B beam (wavelength λ₁), and obliquely irradiating thefront side of the fourth optical film 44 with an R beam (wavelength λ₂).

In the present embodiment, a B beam (wavelength λ₁) emitted from a firstLD 10 is light (S-polarized light) which is linearly-polarized along thefirst direction (the X axis direction). As used herein, S-polarizedlight means linearly polarized light whose polarization axis (i.e., theorientation of its electric field vector) is perpendicular to the planeof incidence (the YZ plane). Linearly polarized light whose polarizationaxis is parallel to the plane of incidence (the YZ plane) is P-polarizedlight. In the present embodiment, an R beam (wavelength λ₂) emitted froma second LD 12 is light (P-polarized light) which is linearly-polarizedalong a second direction (the Z axis direction or the Y axis direction)that is orthogonal to the first direction.

Referring back to FIG. 143, the first optical film 41 includes a firstdichroic film 71 which transmits a B beam and reflects an R beam. Thesecond optical film 42 includes: a λ/2 phase plate 50 for the R beamwhich rotates the polarization direction of an R beam by 90 degrees; anda second dichroic film 72. The second dichroic film 72 transmits an Rbeam and a B beam of S-polarized light, but reflects a B beam ofP-polarized light. The third optical film 43 includes a third dichroicfilm 73 which transmits an R beam and reflects a B beam. The fourthoptical film 44 includes: a λ/2 phase plate 60 for the B beam whichrotates the polarization direction of a B beam by 90 degrees; and afourth dichroic film 74. The fourth dichroic film 74 transmits a B beamand an R beam of P-polarized light, but reflects an R beam ofS-polarized light.

FIG. 15 is a diagram schematically showing the functions of the first tofourth optical films 41 to 44. The thickness of each component elementis exaggerated in the figure. The thickness of any constituent element,when in film shape, may be about 200 nm to several μm, for example. Inthe present embodiment, the first to fourth optical films 41 to 44 aresupported by using four prisms, but any kind of transparent membersother than prisms, e.g., transparent members 70 in plate shapeintersecting each other as shown in FIG. 16, may be used.

FIG. 17A and FIG. 17B are cross-sectional views schematically showingthe operation of the light source device 1400. FIG. 17A shows how Bbeams (wavelength λ₁) emitted from the first LDs 10 on the laser modules100 ₁ to 100 ₃ may be transmitted and reflected. FIG. 17B shows how Rbeams (wavelength λ₂) emitted from the second LDs 12 on the lasermodules 100 ₁ to 100 ₃ may be transmitted and reflected.

As shown in FIG. 17A, a B beam emitted from the first LD 10 on the firstlaser module 100 ₁ is transmitted through the first optical film 41 andthe fourth optical film 44, and goes out from the beam combiner 300. A Bbeam emitted from the first LD 10 on the second laser module 100 ₂ istransmitted through the fourth optical film 44. Specifically, owing tothe action of the λ/2 phase plate 60 for the B beam shown in FIG. 15,after it is converted from S-polarized light to P-polarized light, it istransmitted through the fourth dichroic film 74. After being transmittedthrough the fourth optical film 44 in FIG. 17A, the B beam ofP-polarized light is reflected by the second optical film 42 (seconddichroic film 72), and goes out from the beam combiner 300. A B beamemitted from the first LD 10 on the third laser module 100 ₃ isreflected by the third optical film 43 and thereafter transmittedthrough the second optical film 42, and goes out from the beam combiner300. When transmitted through the second optical film 42, this B beam isnot converted by the λ/2 phase plate 50 for the R beam shown in FIG. 15into P-polarized light, but is intactly transmitted through the seconddichroic film 72.

Next, FIG. 173 and FIG. 15 are referred to. First, as shown in FIG. 173,an R beam emitted from the second LD 12 on the first laser module 100 ₁is transmitted through the third optical film 43 and the second opticalfilm 42, and goes out from the beam combiner 300. When transmittedthrough the second optical film 42, the R beam is converted fromP-polarized light into S-polarized light by the λ/2 phase plate 50 forthe R beam shown in FIG. 15. The second dichroic film 72 included in thesecond optical film 42 transmits an R beam without any dependence onpolarization. An R beam emitted from the second LD 12 on the secondlaser module 100 ₂ is reflected by the first optical film, and thentransmitted through the fourth optical film 44. Specifically, the λ/2phase plate 60 for the B beam shown in FIG. 15 does not effectpolarization conversion for any R beam of P-polarized light, which istherefore transmitted through the fourth dichroic film 74. An R beamemitted from the second LD 12 on the third laser module 100 ₃ istransmitted through the second optical film 42 and thereafter reflectedby the fourth optical film 44, and goes out from the beam combiner 300.When transmitted through the second optical film 42, this R beam isconverted from P-polarized light into S-polarized light by the λ/2 phaseplate 50 for the R beam, and therefore is reflected by the fourthdichroic film 74 included in the fourth optical film 44.

Thus, with the light source device 1400 according to the presentembodiment, the respective B beams and R beams emitted from the threelaser modules 100 ₁ to 100 ₃ can be combined (multiplexed) eithersimultaneously or by way of time division. Each laser modules 100 ₁ to100 ₃ may include a third LD 14 described with reference to the firstembodiment; G beams of S-polarized light (wavelength λ₃) emitted fromthe third LDs 14 will be subjected to transmission, reflection, andpolarization conversion by the first to fourth optical films 41 to 44,in the same manner as are the B beams.

In the above embodiment, B beams of S-polarized light are emitted fromthe first LDs 10, and R beams of P-polarized light are emitted from thesecond LDs 12. The light source device 1400 according to the presentdisclosure is not limited to such an example. The polarization of thelaser beam emitted from each LD may vary depending on the LD structureor the orientation in which the LD chip is positioned. For example, Rbeams of S-polarized light may be emitted from the second LDs 12 asshown in FIG. 17C, whereas B beams of S-polarized light may be emittedfrom first LDs 10. In that case, the fourth dichroic film 74 in thefourth optical film 44 may be changed to a film which reflects an R beamof P-polarized light and transmits an R beam of S-polarized light. Notethat no change will be required in the ability to transmit the B beams.

From the above, the fourth dichroic film 74 may transmit light of thewavelength λ₁ (e.g. a B beam), transmit light of the wavelength λ₂ notpassing through the λ/2 phase plate 50 for the wavelength λ₂ (λ/2 phaseplate for the R beam), and reflect light of the wavelength λ₂ havingpassed through the λ/2 phase plate 50 for the wavelength λ₂.

Embodiment 3

Hereinafter, with reference to FIG. 18, an optical engine according toan embodiment of the present disclosure will be described.

The optical engine 2000 according to the present embodiment includes alight source device 1500, optics 600, a spatial light modulator 700, andprojection optics 800. The light source device 1500 may be a lightsource device according to the present disclosure, and may have astructure similar to that of the light source device 1000 shown in FIG.1, for example. A laser beam going out from the light source device 1500enters the optics 600. In FIG. 18, the laser beam is schematicallyrepresented as a region between a pair of broken lines. The laser beamgoing out from the light source device 1500 is, as has been describedearlier, a beam in which laser beams emitted from the plurality of LDs10, 12 and 14 are combined (multiplexed). Therefore, the laser beamgoing out from the light source device 1500 is a bundle of laser beams(an R beam, a G beam, and a B beam). The diameter (beam diameter) ofeach of the R beam, the G beam, and the B beam may be defined by thesize of a region that has an optical intensity which is e.g. 1/e² orgreater with respect to the optical intensity at the respective beamcenter. Herein, e is Napier's constant (about 2.71). The beam diametermay be defined based on other standards. An R beam, a G beam, or a Bbeam emitted from a laser diode does not have a circular cross-sectionalshape, but rather an elliptical cross-sectional shape. Immediately aftergoing out from the light source device 1500, the R beam, the G beam, andthe B beam have not been uniformly mixed, and their radiancedistribution is not uniform. Before the spatial light modulator 700 isirradiated with the laser beam, the bundle of the R beam, the G beam,and the B beam may desirably be subjected to homogenization in order torender the radiance distributions of these beams as spatially uniform aspossible.

The spatial light modulator 700 is irradiated with a laser beam whichhas passed through a portion of the optics 600 that achieves theaforementioned homogenization. The optics 600 include a collimating lens680 and a reflection mirror 690, such that the reflection mirror 690directs the laser beam toward the spatial light modulator 700. Thespatial light modulator 700, which is composed of e.g. a digital micromirror device (DMD) or an image displaying panel such as a liquidcrystal display panel (LCD), modulates the intensity distribution of thelaser beam so that it will exhibit an image pattern constituting amotion video or a still image. The spatial light modulator 700 receivesimage data from an image processor not shown, and performs an operationfor displaying. The projection optics 800 allows a laser beam havingbeen modulated by the spatial light modulator 700 to be projected ontothe surface of an object (e.g., a screen or a wall surface of abuilding), thus creating an image. The projection optics 800 may includea plurality of lenses for altering the lateral magnification ofdisplaying.

The optics 600 according to the present embodiment include: a converginglens 620 to focus a laser beam (a bundle of the R beam, the G beam, andthe B beam) going out from the light source device 1500; and anintegrator (a multiplexing optical component) 640 through which thelaser beam having been focused by the converging lens 620 is passed. Foran enhanced homogeneity of light, the converging lens 620 preferably hasa large aberration (e.g., spherical aberration). The integrator 640includes a rod integrator and/or a light tunnel, for example. As a laserbeam passes inside the integrator 640, the laser beam will repeatedlyundergo reflection, whereby its spatial mixing is promoted. As a resultof such multiple reflections, the intensity distribution in a planeperpendicular to the propagation direction of the laser beam becomesmore uniform than before entering the integrator 640. As suchhomogenization of intensity distribution progresses with respect to eachof the R beam, the G beam, and the B beam, white light which isuniformed as a whole is generated. Note that the R beam, the G beam, andthe B beam do not need to simultaneously propagate inside the integrator640, but may propagate therein by way of time division according to thepresent embodiment. This will allow a full-color image to be displayedby one spatial light modulator 700 (field sequential method). Theoptical engine 2000 according to the present embodiment creates an Rimage, a G image, and a B image with laser light which is superior inmonochromaticity to that from LEDs, and thus may provide a greater colorgamut for expression.

In the present embodiment, the optics 600 further include an arraytoroidal lens 660 disposed between the lens 620 and the integrator 640.Each of the R beam, the G beam, and the B beam has, after being emittedfrom the LD, an elliptical beam shape having a minor axis and a majoraxis in a far field pattern. The beam divergence angle is relativelysmall along the minor axis direction, but relatively large along themajor axis direction. The array toroidal lens 660 functions to enlargethe beam divergence angle in directions of small divergence angle. Thearray toroidal lens 660 according to the present embodiment includesfour contiguous toroidal lens regions 66. The number of toroidal lensregion 66 may desirably be three or more. In each toroidal lens region66, a curvature in a plane that contains the beam propagation directionand the minor axis of the beam diameter (the YX plane in FIG. 18) isgreater than a curvature in a plane that contains the propagationdirection and the major axis (i.e., the YZ plane in FIG. 18). Sucharrangement allows a beam to be selectively diverged in directions ofrelatively small divergence angle.

Thus, when a laser beam having anisotropy in terms of divergence angleis incident on the integrator 640, the array toroidal lens 660 enlargesthe beam divergence angle so as to increase the number of multiplereflections occurring inside the integrator 640. When a light tunnel isused as the integrator 640, insertion of the array toroidal lens 660allows the length of light tunnel to be reduced from about 100 mm toabout 30 mm, for example. According to the present embodiment, whiledownsizing the optics 600 by reducing the length of the integrator 640,illumination light with an enhanced in-plane uniformity of radiance canbe generated. As a result, a high image quality can be realized that hasnot been attainable with conventional projectors.

Without being limited to the optical engine 2000 according to thepresent embodiment, an optical engine according to the presentdisclosure may take a variety of arrangements. An R beam, a G beam, anda B beam may simultaneously go out from the light source device 1500,and be split into an R beam, a G beam, and a B beam by a beam splitterhaving wavelength selectivity. In that case, the R beam, the G beam, andthe B beam are to be modulated by separate spatial light modulators.

Each embodiment described above is an exemplary illustration of a lightsource device or an optical engine that embodies the technologicalconcept of the present invention, rather than a limitation to thepresent invention. The present specification is not intended to limitany member that is recited in the claims to a member in an embodiment.Unless otherwise specified, the dimensions, materials, shapes, relativepositioning, etc., of the component parts described in each embodimentare mere examples for explanation purposes, rather than limiting thescope of the present invention. The elements constituting the presentinvention may be implemented in such a manner that a plurality ofelements are composed of the same single member that serves as theplurality of elements, or that the functions of one member is splitamong a plurality of members.

A light source device according to the present disclosure is applicableto various technological fields. For example, it may be used in opticalengines, lighting devices, and headlamps for onboard uses. An opticalengine according to the present disclosure is applicable to a displaydevice such as projector or a rear-projection television.

What is claimed is:
 1. An optical engine, comprising: at least one lightsource device configured to emit a plurality of laser beams, each of thelaser beams having an elliptical beam shape having a minor axis and amajor axis; a converging lens configured such that the laser beams areincident thereto; an array toroidal lens configured such that the laserbeams passed through the converging lens are incident thereto andincluding a plurality of toroidal lens regions, each of the toroidallens regions has a first curvature in a plane that contains apropagation direction of the laser beam and the minor axis and a secondcurvature in a plane that contains the propagation direction and themajor axis, the first curvature being greater than the second curvature;and an integrator configured such that the laser beams passed throughthe array toroidal lens are incident thereto.
 2. The optical engine ofclaim 1, wherein a number of toroidal lens region is three or more. 3.The optical engine of claim 1, wherein the integrator comprises a rodintegrator or a light tunnel.
 4. The optical engine of claim 1, furthercomprising: a spatial light modulator configured to be irradiated withthe laser beam having passed through the integrator; and projectionoptics configured to project the laser beam having been modulated by thespatial light modulator.
 5. The optical engine of claim 1, wherein thelight source device includes: at least one first laser diode configuredto emit a first laser beam; and at least one second laser diodeconfigured to emit a second laser beam having a wavelength which islonger than a wavelength of the first laser beam.
 6. The optical engineof claim 5, wherein the light source device includes a hermetic packagehousing the first laser diode and the second laser diode.
 7. The opticalengine of claim 5, wherein the light source device includes a pluralityof collimating lenses including at least one first collimating lensconfigured to be passed through by the first laser beam and at least onesecond collimating lens configured to be passed through by the secondlaser beam.
 8. The optical engine of claim 5, wherein the light sourcedevice includes wiring for connecting the first laser diode and thesecond laser diode respectively to a plurality of terminals that areelectrically independent of each other.
 9. The optical engine of claim5, wherein the light source device includes: a plurality of the firstlaser diodes which are arranged in at least one row; and a plurality ofthe second laser diodes which are arranged in at least one row.
 10. Thelight source device of claim 5, wherein the light source device includesat least one third laser diode configured to emit a third laser beamhaving a wavelength which is between the wavelength of the first laserbeam and the wavelength of the second laser beam.
 11. The light sourcedevice of claim 10, wherein the first laser beam comprises a blue laserbeam; the second laser beam comprises a red laser beam; and the thirdlaser beam comprises a green laser beam.